Refining of crude petroleum



June 11, 1963 s. E. CAMPBELL 3,093,576

REFINING OF CRUDE PETROLEUM Filed Oct. 26, 1959 2 Sheets-Sheet lAdequately Dry Crude Distillation At Substantially Atmospheric Pressure,With Steam Fractionation L .4 l l Nophtho Gas Oil u Lubricating ReducedCrude Distillate t Composite Blend Contact With lO%-25% NaOH Solution AtAbout l50F-250F t Separate Alkaline Solution From Oil t Water Wash OilFree Of'AIkaIi t Dehydrme Recover Organic Acids Contact With About 200%By Volume Of Furfural At About l50 F200 F Separate Oil From ExtractPoraffinlc oil Aromatic Extract :1 Distillation NO. 2 With SteamAromatic Oil Light Naphtho NaOH Contact Stoddard 50mm (Distillation NO.3 With Steam I High cm Number Diesel Fuel [Aromatic Fractionfl'lAlkaline Residuuml INVEA/TUR t figsjduol Liggt l Addmve Cutting OllSCONGO? With Adsorbent Composition June 11, 1963 Filed Oct. 26, 1959Fig.2

s. E. CAMPBELL REFINING OF CRUDE PETROLEUM 2 SheetsSheet 2 DistillationN0.4

Reduced Anhydrous Crude Distillation Under High Vacuum lmm-5rnm MercuryContact With About 200% Plus By Volume 0f Furfural Below 323.6"F

Asphaltic Residuum Separation Paraffinic Lubricating Oil i H 80 TreatSeparate Sludge Vacuum Distill lmm- 5mm. NO. 5

Paraftlnic Fractions Aromatic Extract Vacuum Dlstill lmm- 5mm NO.6

Aror'natlc Fractions Friction,

Alkaline Residuum f' Proportional Blends t Cutting To Meet S.A.E.

Specifications I INVENTOR Test For United States Patent 3,093,576REFINING OF CRUDE PETROLEUM Sumner E. Campbell, 2200 D St., Bakersfield,Calif. Filed Oct. 26, 1959, Ser. No. 848,523 2 Claims. (Cl. 208-221)This invention relates to an improved processing procedure for refiningcrude petroleum containing 20% or more of an homologous series ofaromatic hydro-carbons.

Crude petroleum consists of a complex mixture of hydrocarbons ofdifferent boiling points, with which may be associated certain compoundsconsidered impurities, such as sulphur compounds, organic acids andnitrogeneous bases. Crude petroleum varies widely in its chemicalconstitution. For example, that produced in the State of Pennsylvania isrelatively rich in the paraiin series of hydrocarbons. Crude petroleum,however, produced in the Smackover Field of southern Arkansas, isasphaltic,

and comparatively rich in aromatic hydrocarbons which occur in thiscrude in an homologous series, boiling over a range of temperature.Crude petroleum produced in California usually is also relatively richin hydrocarbons of the aromatic series. Pennsylvania crude is low insultphur, and contains substantially no nitrogen compounds or organicacids. This highly parafinic oil usually has a high content of paraffinwax, which must be removed to obtain sufficiently low pour points forlubricating oils. Smackover crude is generally of two types in one ofwhich there'is sufficient paraflin wax "to make it necessary to separatethis element, if the crude is to be used in the production oflubricating oils. There is also produced in this field, crude that isrelatively free of paraffin wax, so thatno special processing isnecessary for the production of very low pour point lubricating oils.While Pennsylvania crude is substantially free of such compounds asnaphthenic acids, Smackover crude is comparatively rich in these acidiccompounds, which must be removed, both for the production of highquality lubricating oil, as well as to recover them as valuablelay-products. Crude petroleum, as produced in California, is richer. innitrogen compounds than that usually produced anywhere else in theUnited States.

.oil used in the refining steps employed, as described below, which willbe clearly understood by referring to the accompanying diagrams.

The adequately dry crude is first passed through a heating system, suchas a tubular heater, in which the temper- .ature is raised suflicientlyto vaporize that portion of the oil it is desired to distill. Such adistillation system is provided with suitably designed towers in orderto obtain the necessary fractionation. In this operation steam isintroduced for two purposes: one, to facilitate distillation and, two,to avoid any tendency toward decomposition, or cracking, of thehydrocarbons composing the oil. It

In this last mentioned crude, these nitrogen compounds are present intwo forms, about 50% is usual practice to introduce anhydrous ammonia atthe proper point in the system to prevent any corrosion of theequipment, which may occur, particlularly at distillation temperatures,when the crude being refined contains corrosive elements, such assulphur compounds and organic acids.

In the first refining step of the subject process, distillation (No. l)is conducted at substantially atmospheric pressure; the heated vaporsand steam pass upwardly through the fractionating tower, the mostvolatile constituents pass out of the top of the tower to a condenser,where they are converted to liquids, and the first fraction, naphtha, isrecovered, the condensed steam being discarded as Water. The next andless volatile constituents, pass out of the tower lower down, intoanother condenser, are liquefied, and the second fraction, gas oil, isrecovered. The next, and still less volatile constituents, pass out ofthe tower at a still lower level, into another condenser, are liquefied,and the third fraction, light lubricating distillate, is recovered.

' In this new processing procedure, the three normally obtaineddist-illa-tes, having the approximate yields as indicated, naphtha 10%,gas oil 20%, and light lubricating distillate 10%, are incorporated as asingle oil.

The remaining portion of the oil, reduced crude, is not vaporized, andis used as the charging stock for distillation (No. 4) under high acumof 1 min-5 mm. mercury alsolute pressure.

Since the type. of oil being described contains an appreciableproportion of organic acids, such as n-aphthenic acids and phenoliccompounds, and usually has a relatively high sulphur content, it isnecessary to remove these acidic compounds by contacting the oil torender it alkaline with a solution of caustic soda, or its equivalent,of about 10-25% concentration, at about F.-200 F. The alkaline solutioncontaining these acidic impurities, as well as certain sulphur compoundswhich it removes, is separated and the alkaline oil is next thoroughlywashed with water to remove any traces of entrained alkali. From theseparated alkaline solution organic acids are recovered as lay-productsof value, and the sulphur content of the oil is reduced.

In conducting tests on the three distillates mentioned above, obtainedfrom the cited crude, it has been found that from each of them there isextractable 20% or more of hydrocarbons of the aromatic series, whichare soluble in furfural.

The 'water washed oil is next dehydrated, and then contact-ed with about200% by volume of furfural at about 150 F. The oil being processed isseparated into two parts; an extract consisting of the selective solventand the aromatic hydrocarbons it extracts, and a portion which iscomposed of parafiinic and naphthenic hydrocarbons.

This processing operation is conducted by well known highly paraifinicfractions are of increased utility because of their chemicalconstitution. For example, the light naphtha is usable as lighter fluidsince this product must not contain aromatic hydrocarbons or otherimpurities which affect its quality and eificiency in operation. Thereare other uses for such a light paraflinic naphtha which will be readilyapparent to one skilled in the art. The next fraction listed on theaccompanying diagram, Stoddard solvent, when produced by this process,will be found to meet A.S.T.M. Designation: D484-52. The next fraction,of lower volatility, to be used as fuel for the operation of dieselengines, Will be found to have a cetane number of 50 or higher, asrequired in US. Navy specifications, and is also in accordance withA.S.T.M. Designation: D975-53T. This diesel engine fuel, which issubstantially devoid of aromatic hydrocarbons, appreciably decreasescontribution to smog formation, and is therefore highly important incombating this difiicult problem. The residual light lubricating oil,having a viscosity of about 100-110 S.U.S. at 100 F., obtained in thisdistillation, is contacted with a suitable adsorbent, such as silicagel, for lightening its color to the desired degree, which may be waterwhite if the oil is to be used, for example, in the production ofcosmetic compositions, or for other purposes.

Referring to the extract, the separated aromatic hydrocarbons composingthis fraction are entirely freed of furfural and next thoroughlycontacted with a solution of caustic soda, or its equivalent, of about10-25% concentration, to render the oil alkaline, the mixturesutficiently dehydrated to permit distillation (No. 3) andfractionation, introducing steam, only if required, to separate thearomatic hydrocarbon composition into desired fractions, such asbenzene, toluene, the xylenes and higher homologues of aromatichydrocarbons. This treatment accomplishes further reduction of thesulphur content of this aromatic oil, which greatly improves its qualityand utility. This separated anhydrous aromatic oil is utilized for twopurposes: one, to obtain the desired fractions as mentioned above, and,two, because of the chemical constitution of this aromatic hydrocarbonmixture, to provide high solvency for asphaltic binders which holdcarbon particles together to form carbon deposits in internal combustionengines; as well as to provide essential friction reducingcharacteristics, which are furnished by that portion of the aromatichydrocarbon mixture that is of higher viscosity and molecular weight.This entire aromatic composition is added, in necessary and regulatedamount, to the lubricating oil used in internal combustion engines, toprovide the lubricity, especially where clearances are very close, as isthe case with hydraulic valve lifters, in which the highly paraffinicoils are deficient, as well as to furnish solvency that continues itsbeneficial effect, without being lost by volatilization, even at highoperating temperatures in an internal combustion engine. The alkalineresiduum obtained from this distillation (No. 3) in which sulphurcompounds have been highly concentrated, is used as the source materialfor the production of cutting oil compositions.

In the next step of the process, the anhydrous reduced crude issufficiently heated, and distilled (No. 4) under high vacuum of -1 mm.5mm. of mercury absolute pressure. In this operation the oil is separatedinto two parts: lubricating distillate, which must be further refinedfor the production of high quality lubricating oils, and asphalticresiduum, which is further distilled for the production of road oilcompositions, roofing material, and various grades of asphalt.

The lubricating distillate, having a Saybolt Universal viscosity ofabout 65 seconds at 210 F., is contacted with a selective solvent suchas, preferably, furfural, for the purpose of separating hydrocarbons ofthe aromatic series from parafiins and naphthenes. The volume offurfural to be used, which may range between about 200% to 300% byvolume, will depend on the character of the oil being refined. If it hasa high viscosity, a

greater volume of furfural may be required to obtain efficientseparation of the extract from the oil. As already mentioned, usual andwell-known processing procedures are employed in the use of furfural asthe selective solvent. In the process step being described, thetreatment with furfural is conducted at adequately elevated temperature,but sufiiciently below the boiling point of the solvent. By thistreatment there are obtained two portions; a parafiinic lubricating oil,and an aromatic extract. The anhydrous paraflinic lubricating oil, whenentirely freed of furfural, is efiiciently contacted with only thenecessary and minimized amount of 98% sulphuric acid to accomplish therequired purification and decolorization. The acid sludge produced inthis treatment is separated, preferably, by centrifuging, and the acidoil contacted with a solution of caustic soda of about 10%concentration, for neutralization of any acidic compounds present. Thealkaline oil is next dehydrated, distilled and fractionated under highvacuum of 1 mm.-5 mm. of mercury absolute pressure, securing desiredfractions of highly paralfiuic oils from which blends are produced tomeet the specifications for the various S.A.E. grades of lubricatingoil. The residual oil containing the caustic soda used consists of analkaline residuum of about 5% or less in volume. Water is added to thisresidual oil to separate the alkali and recover the highly viscousparafiinic oil, which then must be preferably hot water washed free ofalkali, and dehydrated, to be available for various uses.

Referring now to the aromatic extract, which consists of the furfuralused and the aromatic hydrocarbons which it separates: when thisaromatic oil has been entirely freed of furfural, and the solventrecovered for reuse, the highly aromatic oil is next efiicientlycontacted with a solution of caustic soda of about 25% concentration torender the oil alkaline, the mixture dehydrated, distilled under highvacuum of 1 Inm.5 mm. of mercury absolute pressure, and fractionated toseparate this aromatic oil into desired fractions, having viscositiesfalling within the limits specified by the S.A.E. for each particulargrade of lubricating oil. A necessary and regulated amount of theparticular aromatic fraction which has the viscosity limits specified bythe S.A.E. for a designated grade of lubricating oil, is added to thatfraction of paraflinic lubricating oil obtained by the describedtreatment, which meets the same S.A.E. viscosity specification; thepurpose being to provide these highly paraffinic oils with the frictionreducing characteristics in which they are deficient, so that theblended lubricating oil produced will take just 20 one-pound weights,when tested on a friction machine, to produce a score of about A of aninch on a test bearing. For the purpose of obtaining this information aninstrument has been developed which very efficiently determines theability of an oil to reduce friction (see Patent No. 2,097,716). Othermeans of securing this information can be used, but an accuratemeasurement of the percentage of the aromatic fraction to be added to agiven paraflinic fraction is highly im portant, in order to add onlythat quantity of aromatic oil necessary to obtain the required frictionreducing characteristics, but not an excessive amount which degrades thequality of the oil. The remaining aromatic fractions, of higherviscosity and of reduced sulphur content, are added to the asphalticresiduum to provide and increase the ductility of various grades ofasphalt, including roofing materials, produced from this type of crude.

I. In the refining procedure above described (distillations No. 1 andNo. 2) there are obtained products composed substantially ofhydrocarbons of the A. Parafiin series:

(1) Light naphtha (2) Stoddard solvent (3) High cetane number dieselfuel (4) Light lubricating oil (5) The reduction of sulphur content ofthese refined products increases their value and utility B. Aromaticseries:

(1) The extracted aromatic hydrocarbons obtained in this distillation(No. 3), efficiently fractionated, increases the value of theseseparated, fractions of lowered sulphur content (2) This entire aromatichydrocarbon mixture is utilized, wh=en added to lubricating oil, innecessary amount, to improve the functioning of internal combustionengines and to maintain them in highly efiicient operation (3) Thereduction of sulphur content of these products increases their i alueand utility (4) The alkaline residuum in which sulphur compounds areconcentrated provides source material for cutting oil compositions II.Referring to the refining procedure described under distillations No. 4and No. 5, there are obtained A. Highly parafiinic purified, lubricatingoil fractions of reduced sulphur content B. Highly aromatic fractions ofreduced sulphur content C. Highly viscous aromatic fractions of reducedsulphur content added to the asphaltic residuum, imparting increasedductility D. Alkaline residuum in which sulphur compounds are highly.concentrated provides source material for cutting oil compositions III.The purified highly parafiinic lubricating oils are deficient in theirability to reduce friction. Therefore, a necessary and minimized amountof that particular fraction of aromatic hydrocarbons, of reduced sulphurcontent, which has a viscosity within the viscosity range specified bythe S.A.E. for a designated grade of lubricating oil (i.e.5W-l0W20W-2-03040 50) is added to a paratfinic fraction that has aviscosity also falling within that same range of viscosity required bythe S.A.E. specification for the grade of lubricating oil that hasdesignated. It is essential that the amount of aromatic fraction addedto a paraffinic fraction of the same viscosity range specified by theS.A.E. for the particular grade of lubricating oil desired, be adequate,but not excessive, and regulated to meet the required friction reducingtests, in order to produce this higher quality oil. Distillations No. 1,No. 2 and No. 3 are shown on FIG. 1. Distillations No. 4, No. 5 and No.6 are shown in FIG. 2.

I claim:

1. The process of refining crude petroleum containing 20% or more of anhomologous series of aromatic hydrocarbons, which comprises: (A)distilling the adequate- 1y dry crude at substantially atmosphericpressure, introducing steam, producing a distillate fraction composed ofnaphtha, gas oil and light lubricating oil-and residual reduced crude;treating the composite distillate with caustic soda (NaOH)solutionforming sodium salts of naprrthenic acids and phenolic compoundswhich are contained in the alkaline solution, reducing the sulphurcontent of the oil-and recovering the organic acids from the separatedalkaline solution; dehydrating, and treating the oil with furfural,separating the mixture into a part composed predominantly ofhydrocarbons of the parafiin series-and an extract composed of thefurfural used and hydrocarbon-s of the aromatic series which itseparates; distilling, introducing steam, and fractionating the oilcomposed predominantly of hydrocarbons of the paraffin series, obtaininglight naphtha, Stoddard solvent, high octane number diesel fuel-andresidual light lubricating oil, and treating the light lubricating oilwith adsorbent; separating the furfural from thearomatic oil andrecovering it for reuse as the selective solvent; treating the aromaticoil which has been freed of furfural, with sodium hydroxide (NaOH)solution, reducing the sulphur content, dehydrating, and distilling thealkaline oil, introducing steam, producing aromatic fractions, aromaticadditive compositions-and an alkaline residuum; (B) distilling underhigh vacuum of 1 TIlIIL-S mm. of mercury absolute pressure, of theanhydrous reduced crude, pro ducing lubricating distillatear1d asphalticresiduum; contacting the anhydrous lubricating distillate with furturalat substantially atmospheric pressure and at elevated temperature,separating the mixture into a portion composed predominantly ofhydrocarbons of the parafiin series, and an extract composed of thefur-fural and the aromatic hydrocarbons which it separates; treating theportion composed substantially of hydrocarbons of the parafiin serieswith concentrated sulphuric acid, and removing the formed acid-sludge--neutralizing the acid oil with caustic soda (NaOH) solution,thereby further reducing the sulphur content-dehydrating, distilling andfractionating under high vacuum of 1 min-5 mm. of mercury absolutepressure, and recovering fractions composed predominantly ofhydrocarbons of the paraifin seriesan d an alkaline residuum; mixing thealkaline residuum with sutficient water, heating the mixture to atemperature below 212 F., settling, and separating the alkaline solutionfrom the oil, washing the alkaline oil with Water for the completeremoval of all traces of alkali, dehydrating, and producing ananhydrous, highly viscous, paraflinic lubricating oil; separating thefurfural from the extract and recovering it for reuse as the selectivesolvent, obtaining an oil composed predominantly of hydrocarbons of thearomatic series; contacting this oil with sodium hydroxide (NaOH)solution, further reducing the sulphur oontentdehydrating, andfractionating by distillation under high vacuum of 1 min-5 mm. ofmercury absolute pressure, producing fractions composed predominantly ofhydrocarbons of the aromatic seriesand an alkali residuum.

2. The process as claimed in claim 1 wherein a portion of said aromaticfractions are blended with a portion of said parafiinic fractions ofequivalent viscosity to produce a lubricating oil.

References Cited in the file of this patent UNITED STATES PATENTS1,791,052 Bregi Feb. 3, 1931 1,944,491 Bray Jan. 23, 1934 1,949,989 BrayMar. 6, 1934 1,999,486 Smith Apr. 30, 1935 2,006,095 Bray et al. June25, 1935 2,885,355 Schneider et a1. May 5, 1959 OTHER REFERENCES Nelson:Petroleum Refinery Engineering, fourth edition, 1948, published byMcGraw-Hill Book Co., New York, pages 222, 228 and 347-351 relied on.

1. THE PROCESS OF REFINING CRUDE PETROLEUM CONTAINING 20% OR MORE OF ANHOMOLOGOUS SERIES OF AROMATIC HYDROCARBONS, WHICH COMPRISES: (A)DISTILLING THE ADEQUATELY DRY CRUDE AT SUBSTANTIALLY ATMOSPHERICPRESSURE, INTRODUCING STEAM, PRODUCING A DISTILLATE FRACTION COMPOSED OFNAPHTHA, GAS OIL AND LIGHT LUBRICATING OIL-AND RESIDUAL REDUCED CRUDE;TREATING THE COMPOSITE DISTILLATE WITH CAUSTIC SODA(NAOH)SOLUTION:FORMING SODIUM SALTS OF NAPHTHENIC ACIDS AND PHENOLICCOMPOUNDS WHICH ARE CONTAINED IN THE ALKALINE SOLUTION, REDUCING THESULPHUR CONTENT OF THE OIL-AND RECOVERING THE ORGANIC ACIDS FROM THEDISTILLING, INTRODUCING STEAM, AND FRACTIONATING THE OIL OIL WITHFURFURAL, SEPARATING THE MIXTURE INTO A PART COMPOSED PRODOMINANTLY OFHYDROCARBONS OF THE PARAFFIN SERIES-AND AN EXTRACT COMPOSED OF THEFURFURAL USED AND HYDROCARBONS OF THE AROMATIC SERIES WHICH ITSEPARATES; DISTILLING, INTRODUCING STEAM, AND FRACTIONATING THE OILCOMPOSED PREDOMINANTLY OF HYDROCARBONS OF THE PARAFFIN SERIES, OBTAININGLIGHT NAPHTHA, STODDARD SOLVENT, HIGH CETANE NUMBER DIESEL FUEL-ANDRESIDUAL LIGHT LUBRICATING OIL, AND TREATING THE LIGHT LUBRICATING OILWITH ABSORBENT; SEPARATING THE FURFURAL FROM THE AROMATIC OIL ANDRECOVERING IT FOR REUSE AS THE SELECTIVE SOLVENT; WITH THE AROMATIC OILWHICH HAS BEEN FREED OF FURFURAL, WITH SODIUM HYDROXIDE (NAOH) SOLUTION,REDUCING THE SULPHUR CONTENT, DEHYDRATING, AND DISTILLING THE ALKALINEOIL, INTRODUCING STEAM, PRODUCING AROMATIC FRACTIONS, AROMATIC ADDITIVECOMPOSITIONS-AND AN ALKALINE RESIDUUM; (B) DISTILLING UNDER HIGH VACUUMOF 1 MM.-5 MM. OF MERCURY ABSOLUTE PRESSURE, OF THE ANHYDROUS REDUCEDCRUDE, PRODUCING LUBRICATING DISTILLATE-AND ASPHATIC RESIDUM; CONTACTINGTHE ANHYDROUS LUBIRCATING DISTILLATE WITH FURFURAL AT SUBSTANTIALLYATMOSPHERIC PRESSURE AND AT ELEVATED TEMPERATURE, SEPARATING THE MIXTUREINTO A PORTION COMPOSED PREDOMINATLY OF HYDROCARBONS OF THE PARAFFINSERIES, AND AN EXTRACT COMPOSED OF THE FURFURAL AND THE AROMATICHYDROCARBONS WHICH IS SEPARATES; TREATING THE PORTION COMPOSESSUBSTANTIALLY OF HYDROCARBONS OF THE PARAFFIN SERIES WITH CONCENTRATEDSULPHURIC ACID, AND REMOVING THE FORMED ACID SULDE-NEUTRALIZING THE ACIDOIL WITH CAUSTIC SODA (NAOH) SOLUTION, THEREBY FURTHER REDUCING THESULPHUR CONTENT-DEHYDRATING, DISTILLING AND FRACTIONATING UNDER HIGHVACUUM OF 1 MM.-5 MM. OF MERCURY ABSOLUTE PRESSURE, AND RECOVERINGFRACTIONS COMPOSED PREDOMINANTLY OF HYDROCARBONS OF THE PARAFFINSERIES-AND AN ALKALINE RESIDUUM; MIXING THE ALKALINE RESIDUUM WITHSUFFICIENT WATER, HEATING THE MIXTURE TO A TEMPERATURE BELOW 212*F;SETTLING, AND SEPARATING THE ALKALINE SOLUTION FROM THE OIL, WASHING THEALKOLINE OIL WITH WATER FOR THE COMPLETE REMOVAL OF ALL TRACES OFALKALI, DEHYDRATING, AND PRODUCING AN ANHYDROUS, HIGHLY VISCOUS,PARAFFINIC LUBRICATING OIL; SEPARATING THE FURFURAL FROM THE EXTRACT ANDRECOVERING IT FOR REUSE AS THE SELECTIVE SOLVENT, OBTAINING AN OILCOMPOSED PREDOMINANTLY OF HYDROCARBONS OF THE AROMATIC SERIES;CONTACTING THIS OIL WITH SODIUM HYDROXIDE (NAOH) SOLUTION, FURTHERREDUCING THE SULPHUR CONTENT-DEHYDRATING, AND FRACTIONATING BYDISTILLATION UNDER HIGH VACUUM OF 1 MM.-5 MM. OF MERCURY ABSOLUTEPRESSURE, PRODUCING FRACTIONS COMPOSED PREDOMINATLY OF HYDROCARONS OFTHE AROMATIC SERIES-AND AN ALKALI RESIDUUM.